Merge branch 'restore-header-section-in-doc-ci' into 'master'

Restore header section in CI doc

See merge request gitlab-org/gitlab-ee!7038

doc/ci/README.md

+---
 comments: false
 description: "Learn how to use GitLab CI/CD, the GitLab built-in Continuous Integration, Continuous Deployment, and Continuous Delivery toolset to build, test, and deploy your application."
 ---